One of the disadvantages of prepaid subscriptions offered by many cell phone operators is that outgoing SMS (Short Message Services) are not available to the subscriber when roaming. The reason for the unavailability of these services is that most service operators fail to apply means for carrying out the communication sessions with foreign operators that are required for detecting in real time whether there is sufficient credit in the account of a roaming subscriber for paying for the requested service and for guaranteeing, in real time, the deduction of the respective service fees from such credit.
Obviously, this situation carries a disadvantage for the operator as well. By failing to provide SMS and web browsing services for prepaid subscribers in roaming, a cell phone operator loses significant potential income. A set of standard protocols known as Phase III of Customize Applications for Mobile Enhanced Logic, commonly designated CAMEL3 has been developed to allow for real time charging of Short Messages (SMs) originated by roaming prepaid subscribers based on communication sessions that are carried out for this purpose between the subscriber's home network and the foreign network through which the SM has been originated. Unfortunately, the implementation and use of CAMEL3 involve considerable costs and it is evident that the potential benefits are insufficient to convince hundreds of service operators worldwide to opt for such solution. As a result, operators that do utilize CAMEL3 are unable to make SMS available for prepaid subscribers roaming through any of the large number of foreign networks that have not implemented this system.
Until now, and despite of the resulting loss of profits, many service operators remain without a solution to the above described disadvantage experienced by prepaid subscribers.
WO2007/129315 suggests a CAMEL3-free system that allows prepaid subscribers to extend the range of services available to them while roaming. One disadvantage of the proposed system is its dependency on a client software add-on that must be installed on each prepaid subscription cell phone to be controlled through a dedicated operator's server.
It is therefore within the objects of this invention to provide for cost effective means that will allow a cell phone operator for correlating in real time between the account of a prepaid subscriber and its SMS (and optionally also web browsing) activities while roaming, independently of software installations or modifications to the cellular mobile phone units and without the need to use the CAMEL 3 system.
The following is a description of a typical cellular communication system for which a solution for allowing the use of MO SM (Mobile Originated Short Message) service by prepaid subscribers is required.
An SMSC (short message service center) of a first operator is in communication with a plurality of Mobile Switching Centers (MSCs) of a plurality of other cell phone operators, for receiving SMs addressed to it based on a predetermined SMSC address stored on the SIM (Subscriber Identity Module) card that is installed in each of the cellular mobile phone units subscribed to the first network operator as routing data. Each SM thus received by the SMSC is stored for a predetermined time until successfully delivered to its final destination as determined by the subscriber, in which case the SMSC replies with a delivery confirmation notice. In case the SMSC fails to deliver the SM within a predetermined time limit a failure notice is replied. For the purpose of the present document the network facilities of the operator to whose services the cell phone user is subscribed will be referred to as “Home Network”, while all the network facilities of other operators will be referred to as “Foreign Network/s”. Subscribers of the Home Network operator will be referred to as visitors or roaming, whenever hosted by any of the foreign networks. A Foreign Network currently hosting a subscriber of the Home Network will be referred to as VPLMN (Visited Public Line Mobile Network).
When a cell phone subscriber is hosted by its operator's Home Network (commonly titled Home Public Line Mobile Network (HPLMN)), the short messages (SMs) originated by the subscriber are received at a Mobile Switching Center (MSC) of the home network, which forwards messages to the SMSC. The system recognizes the user data associated with the respective cell phone in its internal Information Registry (IR) (and alternatively in a database that is accessible to foreign operators—herein below Home Location Register (HLR)), and it can decide accordingly whether to forward the message to the SMSC. In case that the user is a prepaid subscriber, the system will temporarily charge/reserve the appropriate service fees from a PrePaid System (PPS) by which the accounts of prepaid subscribers are controlled, until a final delivery status has been replied from the SMSC and consequently the temporarily charged service fees can be permanently charged (upon confirmation of delivery) or re credited to the subscriber's account (upon failure of delivery notice). However, when a cell phone subscribed with the home network operator is hosted by a foreign network\(VPLMN), SM originated by said cell phone are received at a Mobile Switching Center associated with the Visitor Location Register (MSC/VLR) of the foreign network, which has no access to the IR of the home operator. In order to guarantee the share of the foreign operator in the service fees, the MSC/VLR of the foreign network is in communication with the Home Location Register (HLR) of the home network, from which it can retrieve the entitlement of the roaming cell phone to use SMS while roaming. For post paid subscribers an SMS flag in the HLR will normally be enabled, and the foreign operator will be able to charge for the service at a later time in a traditional off-line mechanism for post-payment according to its roaming agreement with the home operator, whereas for prepaid subscribers the SMS flag will normally be disabled. Accordingly, MO SM (Mobile Originated Short Message) of postpaid roaming subscribers will be forwarded by the MSC/VLR of the foreign network to an Inter Working Mobile Switching Center (IW-MSC) operated by the foreign network which forwards SMs through an IW-MSC operated by the home network to the destination SMSC of the home network, while MO-SM of prepaid roaming subscribers will be bounced.
It is therefore an object of the present invention to provide for a solution that allows for real time charging for MO SM of roaming prepaid subscribers to be implemented by a cell phone operator at reasonable cost, that does not require specific adaptations in the systems of foreign network operators or a costly procedure of installing software add-ons on prepaid subscribers' mobile units.